US President Donald Trump has criticised the United Kingdom’s decision to hand over sovereignty of the Chagos Islands to Mauritius, calling it a “big mistake.”
He highlighted that the Diego Garcia military base could be critical in responding to potential threats from Iran.
Trump posted on Truth Social on Wednesday, urging Starmer not to “give away Diego Garcia.” He argued that the UK is losing control of the island through claims he described as “fictitious in nature.”
The president warned that the 100-year lease agreed with Mauritius could limit the strategic use of Diego Garcia, a base jointly used by the UK and US for operations in the Indian Ocean.
Historical context
The Chagos Archipelago was administered as part of Mauritius when under French control from 1715 to 1810. The UK took over the islands in the early 19th century and detached them from Mauritius before granting the latter independence in 1968.
Residents of the islands, mainly Chagossians, were forcibly displaced to establish the Diego Garcia base. Mauritius has been pursuing sovereignty over the islands, winning a legal battle at the International Court of Justice in 2019. The UN subsequently urged the UK to cede control.
The UK-Mauritius agreement
Under the new deal, the UK will maintain a 99-year lease of Diego Garcia with an option to extend, costing roughly £100 million ($135 million) annually.
A UK Foreign Office spokesperson defended the agreement, saying it is “crucial to the security of the UK and our key allies” and ensures the long-term operation of the base. The spokesperson stressed the deal guarantees the future of the strategic military site while keeping the British people safe.
While the US Department of State has officially backed the UK-Mauritius agreement, Trump continued to voice concern. He warned that Diego Garcia, along with the airfield at Fairford, could be necessary to counter potential Iranian threats, particularly regarding nuclear negotiations.
Trump’s statements follow a series of fluctuating US positions: last year he called the deal “great stupidity,” then in February acknowledged it may have been the best option for Starmer.
Strategic importance of Diego Garcia
Diego Garcia serves as a critical military hub for the US and UK. It has been used for major operations, including strikes against the Houthis in Yemen in 2024–2025 and counterterrorism attacks in Afghanistan in 2001.
The base’s strategic location in the Indian Ocean underscores why both Trump and military analysts emphasize its importance amid rising Middle East tensions.
The deal has drawn criticism from some Chagossians, who argue Mauritius has neglected the displaced population for decades. Mauritius denies these claims but the concerns highlight the long-term social and political impacts of the sovereignty transfer.
